package com.eiisan.util;

import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.security.SecureRandom;
import java.util.Random;

/**
 * 验证码处理工具类
 */
public final class VerifyCodeUtil {

    /**
     * 验证码字符,去掉了1,0,i,o几个容易混淆的字符,23456789ABCDEFGHJKLMNPQRSTUVWXYZ
     */
    private static final String VERIFY_CODES = "23456789ABCDEFGHJKLMNPQRSTUVWXYZ";

    private static Random random = new Random();

    /**
     * 输出随机验证码图片流,并返回验证码值
     * @param w
     * @param h
     * @param os
     * @param verifySize
     * @return
     * @throws IOException
     */
    public static String outputVerifyImage(int w, int h, OutputStream os, int verifySize) throws IOException {
        String verifyCode = getRandomToken(verifySize);
        outputImage(w, h, os, verifyCode);
        return verifyCode;
    }

    /**
     * 生成指定验证码图像文件
     * @param w    图像宽度
     * @param h    图像高度
     * @param outputFile 输出文件
     * @param code
     * @throws IOException
     */
    public static void outputImage(int w, int h, File outputFile, String code) throws IOException {
        if (outputFile == null) {
            return;
        }
        File dir = outputFile.getParentFile();
        if (!dir.exists()) {
            dir.mkdirs();
        }
        try {
            outputFile.createNewFile();
            FileOutputStream fos = new FileOutputStream(outputFile);
            outputImage(w, h, fos, code);
            fos.close();
        } catch (IOException e) {
            throw e;
        }
    }

    /**
     * 输出指定验证码图片流
     * @param w    图像宽度
     * @param h    图像高度
     * @param os   输出流
     * @param code 验证码
     * @throws IOException
     */
    public static void outputImage(int w, int h, OutputStream os, String code) throws IOException {
        int verifySize = code.length();
        BufferedImage image = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
        Graphics2D g = image.createGraphics();
        g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

        // 设置边框色
        g.setColor(Color.GRAY);
        g.fillRect(0, 0, w, h);

        Color c = getRandColor(200, 250);
        // 设置背景色
        g.setColor(c);
        g.fillRect(0, 2, w, h - 4);

        // 绘制干扰线
        // 设置线条的颜色
        g.setColor(getRandColor(160, 200));
        for (int i = 0; i < 20; i++) {
            int x = VerifyCodeUtil.random.nextInt(w - 1);
            int y = VerifyCodeUtil.random.nextInt(h - 1);
            int xl = VerifyCodeUtil.random.nextInt(6) + 1;
            int yl = VerifyCodeUtil.random.nextInt(12) + 1;
            g.drawLine(x, y, x + xl + 40, y + yl + 20);
        }

        // 添加噪点
        // 噪声率
        float yawpRate = 0.03f;
        int area = (int) (yawpRate * w * h);
        for (int i = 0; i < area; i++) {
            int x = VerifyCodeUtil.random.nextInt(w);
            int y = VerifyCodeUtil.random.nextInt(h);
            int rgb = getRandomIntColor();
            image.setRGB(x, y, rgb);
        }

        // 使图片扭曲
        shear(g, w, h, c);

        int fontSize = h - 4;
        Font font = new Font("Times New Roman", Font.ITALIC, fontSize);
        g.setFont(font);
        // 取随机产生的认证码
        char[] chars = code.toCharArray();
        for (int i = 0; i < verifySize; i++) {
            g.setColor(getRandColor(30, 130));
            AffineTransform affine = new AffineTransform();
            affine.setToRotation(Math.PI / 4 * random.nextDouble() * (random.nextBoolean() ? 1 : -1),
                    (w / verifySize) * i + fontSize / 2, h / 2);
            g.setTransform(affine);
            g.drawChars(chars, i, 1, ((w - 10) / verifySize) * i + 5, h / 2 + fontSize / 2 - 6);
        }

        g.dispose();
        ImageIO.write(image, "jpg", os);
    }

    private static Color getRandColor(int fc, int bc) { //给定范围获得随机颜色
        if (fc > 255){
            fc = 255;
        }
        if (bc > 255){
            bc = 255;
        }
        int r = fc + random.nextInt(bc - fc);
        int g = fc + random.nextInt(bc - fc);
        int b = fc + random.nextInt(bc - fc);
        return new Color(r, g, b);
    }

    private static int getRandomIntColor() {
        int[] rgb = getRandomRgb();
        int color = 0;
        for (int c : rgb) {
            color = color << 8;
            color = color | c;
        }
        return color;
    }

    private static int[] getRandomRgb() {
        int[] rgb = new int[3];
        for (int i = 0; i < 3; i++) {
            rgb[i] = random.nextInt(255);
        }
        return rgb;
    }

    public static String getRandomToken(int length) {
        byte[] b = new byte[length];
        SecureRandom sr = new SecureRandom();
        sr.nextBytes(b);
        return toPrintable(b);
    }

    private static String getRandomToken() {
        return getRandomToken(4);
    }

    private static String toPrintable(byte[] b) {
        final char[] alphabet = VERIFY_CODES.toCharArray();
        char[] out = new char[b.length];
        for (int i = 0; i < b.length; i++) {
            int index = b[i] % alphabet.length;
            if (index < 0) {
                index += alphabet.length;
            }
            out[i] = alphabet[index];
        }
        return new String(out);
    }

    private static void shear(Graphics g, int w1, int h1, Color color) {
        shearX(g, w1, h1, color);
        shearY(g, w1, h1, color);
    }

    private static void shearX(Graphics g, int w1, int h1, Color color) {
        int period = random.nextInt(2);
        boolean borderGap = true;
        int frames = 1;
        int phase = random.nextInt(2);
        for (int i = 0; i < h1; i++) {
            double d = (double) (period >> 1)
                    * Math.sin((double) i / (double) period + (6.2831853071795862D * (double) phase) / (double) frames);
            g.copyArea(0, i, w1, 1, (int) d, 0);
            if (borderGap) {
                g.setColor(color);
                g.drawLine((int) d, i, 0, i);
                g.drawLine((int) d + w1, i, w1, i);
            }
        }
    }

    private static void shearY(Graphics g, int w1, int h1, Color color) {
        int period = random.nextInt(40) + 10;
        boolean borderGap = true;
        int frames = 20;
        int phase = 7;
        for (int i = 0; i < w1; i++) {
            double d = (double) (period >> 1)
                    * Math.sin((double) i / (double) period + (6.2831853071795862D * (double) phase) / (double) frames);
            g.copyArea(i, 0, 1, h1, 0, (int) d);
            if (borderGap) {
                g.setColor(color);
                g.drawLine(i, (int) d, i, 0);
                g.drawLine(i, (int) d + h1, i, h1);
            }
        }
    }
}
